PLANE-STRAIN FRACTURE-TOUGHNESS OF POLYPHENYLENE SULFIDE

The plane strain fracture toughness of polyphenylene sulfide (PPS), te sted with different molecular structures such as linear PPS, heat-trea ted PPS, and branched PPS, was investigated over a wide range of melt viscosity and crystallinity and compared with other mechanical propert ies. The fracture toughness of linear PPS increased with increasing me lt viscosity, and it reached the highest fracture toughness calculated from linear elastic fracture mechanics (LEFM) observed in this study. In this high melt viscosity region, the linear PPS specimen showed sl ow crack growth instead of brittle fracture. Although the tensile prop erties of heat-treated PPS and branched PPS are the same as those of l inear PPS, the fracture toughness of linear PPS is superior. The fract ure toughness is affected by the crystallinity of the specimen, and th e effect of crystallinity on fracture toughness is smaller than that o f melt viscosity and molecular structure.